1. Field of the Invention
The present invention relates to a power supply device for reducing a direct current voltage, and an electric power conversion device using the same.
2. Description of the Related Art
In general, a power supply device for increasing an input voltage is equipped with a step-up-type DC-DC converter, and a power supply device for reducing an input voltage is equipped with a step-down-type DC-DC converter. In any case, a feedback circuit for regulating an output voltage of the DC-DC converter is usually provided.
By the way, when one of power supply voltages provided to both ends of a load is not connected to a ground potential, a larger number of voltages than the number of direct current voltages that can be generated by a power supply system having multiple DC-DC converters can be provided to the load. More specifically, by applying two kinds of voltages generated by the power supply system to both ends of the load, voltages other than the voltage generated by the power supply system can be applied to the load. This method is advantageous when, for example, it is applied to an inverter and the like for generating a quasi-sinusoidal wave using multiple direct current voltages.
In this method explained above, it is important to regulate a voltage applied to a lower potential-side terminal to which an electric current flows via the load from a high potential-side terminal. However, when a regulator and so on is used to regulate the voltage, electric power consumption is likely to be wasted.